From 2 Dimensional to 3 Dimensional: Modeling the Western Gulf Using Recently Acquired Long Offset Seismic and Gravity Data

Marianne Parsons, Anthony Price, John Bain, Shawn Mulcahy, and Robert Pawlowski
Fugro-LCT, Houston , Texas

The subsurface of the western Gulf of Mexico is a complex geological environment that has been evoking recent strong interest from the petroleum industry. In an effort to image deeper structures, and to better understand the geological setting, long offset seismic and marine gravity data have recently been acquired throughout this area for the period mid 2003 to present.

In the seismic processing of the initially acquired lines, 2 dimensional gravity data was used to improve seismic modeling and imaging of salt. This proved to be valuable in the Pre-Stack Depth Migration phase of processing, so that when a network of seismic and gravity lines had been acquired a 3 dimensional earth model was created for the area of interest. Thus such a model was used in assessing 3 dimensional shapes – particularly salt.

The complex nature of this area encompasses sutured salt canopies, hidden salt roots and evacuated/welded basins. The ability to model these features using gravity, in both a forward modeling and inversion mode, prior to the Pre-Stack Depth Migration process saves valuable time and money in the seismic processing sequence.

Insight is also gained into deeper features such as basement structure and crustal composition. Throughout the 3 dimensional modeling and the 2 dimensional seismic interpretation phases, geophysicists working on the project had access to both gravity and seismic data. Integration and interaction throughout the process was crucial in obtaining a better understanding of the Western Gulf.

AAPG Search and Discovery Article #90032©2004 GCAGS 54th Annual Convention, San Antonio, Texas, October 10-12, 2004